The problem hasn't disappeared, and it's there even when I try to open mobi books.
My battery was at 25% or so but not low. I did hard resets, a factory reset, and it didn't change anything. Actually, I think it's worse now.
Amazon called me this morning and they're sending me a new one. The CS wasn't able to repair it either despite trying to help me for over 15 minutes. I've never read 8 books in a month in my whole life, and this month I did, but now my Kindle's broken... Oh well. Hopefully the new one will be nicer to me.
It should be here by Thursday and it'll be given a lot of love... if it works.